repo: look up nullrev context by revnum, not symbolic name
I think lookup of the 'null' symbol should be done via
scmutil.revsymbol() and repo['null'] is only supported for historical
reasons. However, repo[nullrev] is fine, so we can switch to that
instead of switching to scmutil.revsymbol('null').
Differential Revision: https://phab.mercurial-scm.org/D4780
@echo off
powershell -NoProfile -ExecutionPolicy unrestricted -Command "& '%~dp0\editmergeps.ps1' %*"